1. Field of the Invention
The present invention pertains to a patient interface for use in a non-invasive pressure support or ventilation system that supplies a flow of gas to the airway of a patient, and, in particular, to a patient interface having a seal member that is selectively adjustable relative to a faceplate or other seal supporting structure so that the user can control the position of the seal to optimize comfort and fit while also minimizing gas leak.
2. Description of the Related Art
There are numerous situations where it is necessary or desirable to deliver a flow of gas non-invasively to the airway of a patient, i.e., without intubating the patient or surgically inserting a tracheal tube in the esophagus. For example, it is known to ventilate a patient using a technique known as non-invasive ventilation (NIV). It is also known to deliver a pressure support therapy to treat a medical disorder, such as sleep apnea syndrome, in particular, obstructive sleep apnea (OSA), cheynes-stokes respiration, and congestive heart failure. Typical pressure support therapies include providing a continuous positive airway pressure (CPAP) or a variable airway pressure to the airway of the patient. Examples of variable airway pressure therapies include providing a bi-level pressure that varies with the patient's respiratory cycle, a proportional pressure that varies the delivered pressure based on the patient's respiratory effort or flow, and an auto-titrating pressure that varies the delivered pressure based on the monitored condition of the patient.
Non-invasive ventilation and pressure support therapies involve the placement of a patient interface, which is typically a nasal or nasal/oral mask, on the face of a patient to interface the ventilator or pressure support system with the airway of the patient so that a flow of gas can be delivered from the pressure/flow generating device to the airway of the patient. Typically patient interfaces include a mask shell having a cushion attached to the shell that contacts the surface of the patient. The mask shell and cushion are held in place by a headgear that wraps around the head of the patient. The mask and headgear form the patient interface assembly. A typical headgear includes flexible, adjustable straps that extend from the mask to attach the mask to the patient.
Because such masks are typically worn for an extended period of time, a variety of concerns must be taken into consideration. For example, in providing CPAP to treat OSA, the patient normally wears the patient interface all night long while he or she sleeps. One concern in such a situation is that the patient interface is as comfortable as possible, otherwise the patient may avoid wearing the interface device, defeating the purpose of the prescribed pressure support therapy. It is also important that the interface device provides a tight enough seal against a patient's face without discomfort so that gas leakage from the system at the patient-seal interface is minimized. A dilemma arises in that in order for the mask to maintain a seal without any undue gas leaks around the periphery of the mask, the mask may be compressed against the patient's face, which may decrease comfort.
Many patient interfaces have been developed that attempt to balance the competing interests of patient comfort versus minimizing leakage. In addressing this issue, many patient interfaces have focused on the design of the cushion. Early cushion designs were typically a flap of material or a balloon, i.e., air-filled cushion, that contacted the face of the user. Further design developments including contouring the patient contacting portion of the cushion and/or making the seal customizable to the surface or underlying tissues of the user. Still further cushions have employed multiple flaps so that the outermost flap provides a sealing function. See, e.g., U.S. Pat. No. 4,971,051 to Toffolon.
In addition, U.S. Pat. No. 6,530,373 (“the '373 patent”) discloses a patient interface in which the position of the seal relative to the conduit is adjustable over discrete positions. This is done in the '373 patent because there is little or no control of the position of the conduit relative to the patient's face. Allowing the seal position to be adjusted allows the seal to set to a proper angle on the user depending on the position of the conduit. This patient interface, however, does not provide a stable platform on which the seal is mounted.
Although these conventional patient interfaces have advanced the art, the need still exists for a patient interface that improves upon existing devices, for example, to maximize patient comfort while minimizing leak, during delivery of a positive airway pressure or flow of gas to the airway of the user. In addition, existing patient interfaces also may not provide a stable platform that supports the cushion on the patient's face.